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Berlin 2005 – scientific programme

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M: Metallphysik

M 48: Mechanische Eigenschaften IV

M 48.3: Talk

Tuesday, March 8, 2005, 17:00–17:15, TU H111

Interaction of screw dislocations with coherent twin-boundaries in fcc metals — •Zhao-Hui Jin1, Karsten Albe1, and Horst Hahn21TU Darmstadt, Institut für Materialwissenschaft, Petersenstr. 23, D-64287 Darmstadt — 2Forschungszentrum Karlsruhe, Institut für Nanotechnologie, D-76021 Karlsruhe

The concept of the generalized stacking fault (GSF) energy, which is generally considered to be crucial for understanding nucleation of lattice dislocations, is re- examined for various FCC metals. In this paper we study the scenario of a pure screw dislocation that starts moving towards an elementary coherent twin boundary. In order to carry plasticity further away the dislocation has to cross the twin boundary and change to a different glide plane, where it moves on. This is equivalent to a renucleation process of the dislocation, which has to be activated against constrictions of the pre-existing twin boundary. Be means of molecular dynamics simulations we can identify a crystallographically unexpected behaviour of this crossing process in Ni, Cu and Al. From the GSF energy and the driving force acting on the dislocation we can estimate the nucleation thresholds and explain the nature of bifurcated slips either into the twin lattice or along the twin plane.

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